全文获取类型
收费全文 | 1841篇 |
免费 | 39篇 |
国内免费 | 5篇 |
专业分类
化学 | 1361篇 |
晶体学 | 14篇 |
力学 | 23篇 |
综合类 | 1篇 |
数学 | 79篇 |
物理学 | 407篇 |
出版年
2021年 | 9篇 |
2020年 | 9篇 |
2019年 | 19篇 |
2018年 | 11篇 |
2017年 | 10篇 |
2016年 | 17篇 |
2015年 | 33篇 |
2014年 | 30篇 |
2013年 | 78篇 |
2012年 | 72篇 |
2011年 | 97篇 |
2010年 | 50篇 |
2009年 | 37篇 |
2008年 | 93篇 |
2007年 | 111篇 |
2006年 | 96篇 |
2005年 | 80篇 |
2004年 | 76篇 |
2003年 | 78篇 |
2002年 | 84篇 |
2001年 | 54篇 |
2000年 | 46篇 |
1999年 | 23篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 21篇 |
1995年 | 13篇 |
1994年 | 24篇 |
1993年 | 24篇 |
1992年 | 26篇 |
1991年 | 26篇 |
1990年 | 24篇 |
1989年 | 17篇 |
1988年 | 23篇 |
1987年 | 31篇 |
1986年 | 25篇 |
1985年 | 35篇 |
1984年 | 23篇 |
1983年 | 16篇 |
1982年 | 22篇 |
1981年 | 22篇 |
1980年 | 22篇 |
1979年 | 29篇 |
1978年 | 26篇 |
1977年 | 24篇 |
1976年 | 24篇 |
1975年 | 30篇 |
1974年 | 25篇 |
1973年 | 20篇 |
1972年 | 10篇 |
排序方式: 共有1885条查询结果,搜索用时 15 毫秒
151.
Yellow and colourless complexes of molybdophosphate were investigated by the use of laser Raman spectroscopy. Two kinds of yellow molybdophosphates were identified in the weakly acidic solutions: 12-molybdophosphoric and 11-molybdophosphoric acid which are in equilibrium in solution at pH 1-2. When excess phosphate is present, the colourless molybdophosphate is formed. This complex exists in the solutions of pH 4-1 under the condition of excess phosphate ([P]/[Mo] > 2). This complex was confirmed to be P2Mo5O6?23 and is so stable that the yellow molybdophosphate is converted into the colourless by excess phosphate. 相似文献
152.
The border luminance of the test stimulus between the natural and unnatural object color, yynBu was obtained for different spatial sizes of the immediate surround to prove that nBu can be determined based on a new recognized visual space of illumination (RVSI) that is assumed to be constructed for the immediate surround separately from the RVSI for the subjects room itself. The nBu of five test stimuli were determined for six different sizes covering from zero to 1866 cm2 with four different lightnesses, N4, N6 and N8, while keeping the room illuminance constant at 100 or 600 lx. The results showed that luminance of the border nBu gradually decreased as the size of the immediate surround was increased and that the decrease was larger for immediate surround with lower lightness. The results were interpreted as showing a new RVSI constructed for the spatial extent of the immediate surround of the test stimulus, and the RVSI was more completely constructed for larger spatial size of the immediate surround. © 2005 The Optical Society of Japan 相似文献
153.
N-Phenethylhexadecanamide was isolated from the MeOH extract of the fruiting bodies of the mushroom Laetiporus sulphureus together with eburicoic acid. Their structures were elucidated by spectroscopic methods. 相似文献
154.
Chao Y Chang P Abe K Abe K Aihara H Akai K Akatsu M Akemoto M Asano Y Aushev T Bahinipati S Bakich AM Bay A Bedny I Bitenc U Bizjak I Bondar A Bozek A Bracko M Brodzicka J Browder TE Chen A Chen KF Chen WT Cheon BG Chistov R Choi SK Choi Y Chuvikov A Dalseno J Danilov M Dash M Dragic J Drutskoy A Eidelman S Eiges V Enari Y Fang F Flanagan J Fratina S Furukawa K Gabyshev N Garmash A Gershon T Gokhroo G Golob B Haba J Hastings NC Hayasaka K Hayashii H Hazumi M Hinz L Hokuue T Hoshi Y Hou S Hou WS 《Physical review letters》2005,94(18):181803
We report the observation of the decay B0-->pi(0)pi(0), using a 253 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) collider. The measured branching fraction is B(B0-->pi(0)pi(0))=(2.3(+0.4+0.2)(-0.5-0.3))x10(-6), with a significance of 5.8 standard deviations including systematic uncertainties. We also make a measurement of the direct CP violating asymmetry in this mode. 相似文献
155.
Aliu E Andringa S Aoki S Argyriades J Asakura K Ashie R Berns H Bhang H Blondel A Borghi S Bouchez J Burguet-Castell J Casper D Cavata C Cervera A Cho KO Choi JH Dore U Espinal X Fechner M Fernandez E Fukuda Y Gomez-Cadenas J Gran R Hara T Hasegawa M Hasegawa T Hayashi K Hayato Y Helmer RL Hill J Hiraide K Hosaka J Ichikawa AK Iinuma M Ikeda A Inagaki T Ishida T Ishihara K Ishii T Ishitsuka M Itow Y Iwashita T Jang HI Jeon EJ Jeong IS Joo K Jover G Jung CK Kajita T Kameda J Kaneyuki K Kato I 《Physical review letters》2005,94(8):081802
We present results for nu(mu) oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced nu(mu) beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy-dependent disappearance of nu(mu), which we presume have oscillated to nu(tau). The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma). 相似文献
156.
We introduce Hilbert phase microscopy (HPM) as a novel optical technique for measuring high transverse resolution quantitative phase images associated with optically transparent objects. Because of its single-shot nature, HPM is suitable for investigating rapid phenomena that take place in transparent structures such as biological cells. The potential of this technique for studying biological systems is demonstrated with measurements of red blood cells, and its ability to quantify dynamic processes on a millisecond scale is exemplified with measurements of evaporating micrometer-sized water droplets. 相似文献
157.
Aiura Y Yoshida Y Hase I Ikeda SI Higashiguchi M Cui XY Shimada K Namatame H Taniguchi M Bando H 《Physical review letters》2004,93(11):117005
We present detailed energy dispersions near the Fermi level along the high symmetry line GammaX on the monolayer and bilayer strontium ruthenates Sr2RuO4 and Sr3Ru2O7, determined by high-resolution angle-resolved photoemission spectroscopy. A kink in the dispersion is clearly shown for the both ruthenates. The energy position of the kink and the slope in the low-energy part near the Fermi level are almost identical between them, whereas the dispersion in the high-energy part varies, like the behavior of the kink for the cuprate superconductors. 相似文献
158.
An equilateral-triangular shape of three alpha clusters surrounded by excess neutrons is suggested for 14C, based on the molecular-orbit model. It is found that the attractive interaction between an excess neutron and an alpha particle stabilizes the K(pi)=0(+) and 3(-) rotational bands, which demonstrates an equilateral-triangular symmetry. This K(pi)=3(-) band at 3 MeV below the 10Be+alpha threshold energy corresponds to the experimentally observed band built on top of the second 3(-) state. A positive-parity rotational band (0(+), 2(+), 4(+)) arises similarly. These two bands suggest a molecular 3-alpha structure stabilized by the excess neutrons and can be viewed as a realization of the alpha crystallization in the dilute nuclear medium. 相似文献
159.
160.